Disclosed herein is a propulsion apparatus for ships. The propulsion apparatus, which includes a front propeller and a rear propeller to rotate in opposite directions and provides propulsion power to propel a hull of a ship, includes a power unit to supply power to rotate the rear propeller, a main shaft to transfer the power supplied from the power unit to the rear propeller, a hollow shaft extending in a longitudinal direction of the main shaft to allow the main shaft to pass therethrough and coupled to the front propeller, a drive motor including a rotor coupled to an outer circumferential surface of the hollow shaft and a stator supported by the hull, the drive motor rotating the hollow shaft in a direction opposite to a direction of rotation of the main shaft, and an electricity supply unit to supply electricity to the drive motor.